A relatively simple(I think) quality of life change that would be nice.

When CTRL clicking an item stack that is larger than what your character can carry, allow the game to move the max amount constraint to remaining inventory weight allowed. Instead of having to manually split stacks then moving them over.

Additional functionality could be in the form of first CTRL click will add items from stack that will bring you to max unencumbered weight while a second click (at max unencumbered) will move items over to max encumbered weight.